Momentum transfer to small particles by aloof electron beams

TL;DR

This paper calculates the momentum transfer from fast electrons to nanoparticles, showing that electron beam forces can rival optical tweezers, enabling new studies of trapped particles in electron microscopes.

Contribution

It provides a detailed calculation of momentum transfer to small particles by aloof electron beams, highlighting potential for novel experimental techniques.

Findings

Electron beam forces are comparable to optical tweezers.

Momentum transfer varies with particle size and material.

Potential to study trapped particles inside electron microscopes.

Abstract

The force exerted on nanoparticles and atomic clusters by fast passing electrons like those employed in transmission electron microscopes are calculated and integrated over time to yield the momentum transferred from the electrons to the particles. Numerical results are offered for metallic and dielectric particles of different sizes (0-500 nm in diameter) as well as for carbon nanoclusters. Results for both linear and angular momentum transfers are presented. For the electron beam currents commonly employed in electron microscopes, the time-averaged forces are shown to be comparable in magnitude to laser-induced forces in optical tweezers. This opens up the possibility to study optically-trapped particles inside transmission electron microscopes.